You don't have to get one, Apple is just the pioneering company, much like they are for display port right now, and how they were for USB in the past

I'd expect that in a year from now you'll have a few PC's with it, and within 5 years, if its all intel says its gonna be, it'll the universal standard

The connector is shaped identically to a USB connector, it just has more connections inside, so if the device is light peak capable it'll use it, but if its USB3/2 then it'll downgrade to USB 3/2 performance